Results from an analysis of plant remains found in faecal droppings of kakapo (Strigops habroptilus) collected from 1981 to 1998 on Codfish Island (Whenua Hou) and Stewart Island, were analysed statistically to identify patterns in the birds’ diet related to breeding. Females were more likely to have eaten podocarp fruit or leaves of trees or shrubs; males to have eaten fern and Lycopodium rhizomes, monocots (in breeding years), and manuka fruit (in non-breeding years). Podocarp fruits were much more prevalent in kakapo diets in breeding than in non-breeding years. When podocarp fruits were available in breeding years, kakapo were less likely to have eaten several other foods. Conversely, Blechnum fern fronds appeared more frequently in the droppings of females in breeding than in non-breeding years. As podocarp fruits increased in prevalence in the diets of both males and females during the summers of breeding years, the incidence of many other foods declined. The incidence of Hall’s totara leaf in the diet of females increased during summer in non-breeding years, but decreased in breeding years.
We recorded the fate of brown kiwi (Apteryx mantelli) eggs collected from Northland forests for artificial incubation at Auckland Zoo. The hatchability of eggs of different ages were combined with known rates of egg losses in the wild to derive models which predicted that optimal hatching success (>64%) was when the oldest egg in a brown kiwi nest was 41-57 days old at the time the eggs were collected. Collection before this interval risked egg failure resulting from unknown developmental problems associated with artificial incubation of freshly-laid eggs, whereas later collection of clutches risked failures in the wild before the eggs were collected.
Information on the breeding ecology of Auckland Is snipe (Coenocorypha aucklandica aucklandica), Antipodes Is snipe (C. aucklandica meinertzhagenae), and Campbell Is snipe (Coenocorypha undescribed sp.) is summarised. Auckland Is snipe laid between Sep and Jan (peak late Nov), whereas Antipodes Is snipe laid from Aug to early Nov, with a 2nd pulse of breeding from late Jan to Mar. The 5 breeding events recorded for Campbell Is snipe were from clutches estimated to have been commenced between 11 Nov and 8 Jan. All 3 taxa laid 2 large eggs (each 19-22% of female body weight) in nests that were well concealed amid dense vegetation. Chicks left the nest soon after hatching, with each chick cared for by a single adult. Exceptions to this were adult Auckland Is snipe seen with 2 or 3 young chicks on 3 occasions. Chicks remained with adults until down-free and capable of flight. The only notable differences from the more thoroughly-studied Snares Is snipe (C.aucklandica huegeli) and Chatham Is snipe (C. pusilla) were the earlier breeding by Antipodes Is snipe, and its bimodal breeding season. Snipe were encountered more frequently on the Auckland Is (0.6 person–h-1 of walking on Adams I) than on Antipodes I (0.2 person–h-1) and this was also reflected in the frequency with which breeding events were recorded. We suggest that the impact of house mice (Mus musculus) on the invertebrate food supply available for snipe is the most plausible explanation for the much lower abundance of snipe on Antipodes I.
King shags (Leucocarbo carunculatus) dispersing to feeding areas from breeding colonies on the Trio Islands and Stewart Island began to leave colonies around dawn, and most had left by mid-morning. Foraging birds were distributed throughout Admiralty Bay, the average distance from the colony was c. 10 km, and were observed only rarely where the water depth was >50 m. Greater areas of mussel farms in inshore waters could potentially affect king shags by restricting the area available for foraging.
The breeding biology of kakapo (Strigops habroptilus) was investigated on offshore island refuges between 1990 and 2002. Male kakapo typically attended their display territories between October to April, with the primary courtship display, “booming”, usually beginning in January and ending in March. Mating was recorded from late December to March, with the median mating date falling in late January. Eggs were laid from early January to late March, with median dates of 24 January on Little Barrier Island and 7 February on Codfish and Pearl Islands. Females typically occupied a nest site eight days after their last mating (n = 44) and laid their first egg two days later (n = 40). Subsequent eggs were laid at three day intervals (n = 41). The mean and modal clutch sizes were 2.53 and 3 respectively, (range = 1 – 4, n = 54). Mean mass of fresh eggs was 40.53g (n = 122). Incubation began immediately after the first egg had been laid and the average incubation period was 30 days (n = 28). Mean nestling and fledgling periods were 72.4 (n = 27) and 246 days (n = 25) respectively. Male chicks began to grow more rapidly than females approximately one third through the nestling period. The mean fledging weights of 14 male and 14 female chicks were 1.93 and 1.72 kg respectively. Male kakapo are capable of mating at five years of age. Three known-age females first nested at 9, 10 and 11 years of age, respectively. Comparison with close relatives suggests that some aspects of kakapo breeding biology are evolutionarily conservative.
The anticoagulant brodifacoum is widely used for the control and eradication of vertebrate pests in New Zealand. During poisoning operations with this toxin, some native birds eat baits and die. Because brodifacoum persists in the environment, other birds may suffer secondary poisoning from eating animals that have ingested the poison baits.We describe here high mortality of New Zealand dotterels (Charadrius obscurus) following an aerial brodifacoum operation at Tawharanui Regional Park, North Auckland, in 2004. At least 50% of the dotterels in the area at the time of the operation disappeared or were found dead; one bird found freshly dead had a high liver level of brodifacoum residue. Sandhoppers (Talorchestia spp.) are a common food item of New Zealand dotterels. Sandhoppers at Tawharanui ate baits and accumulated brodifacoum and provided a potential route for transmission of the toxin to dotterels. Three pied stilts (Himantopus himantopus) and one spur-winged plover (Vanellus miles novaehollandiae) were also found dead. These records appear to be the first to document probable secondary poisoning of shorebirds in New Zealand. There was no apparent mortality of variable oystercatchers (Haematopus unicolor). Measures are suggested to reduce shorebird mortality in future operations of this type. Monitoring of New Zealand dotterels and other shorebirds during other types of poisoning operations in coastal areas is also recommended.
The “hakawai” is a rarely-heard but dramatic nocturnal aerial display performed by Coenocorypha snipe. Although much has been written about the hakawai formerly heard on islands off Stewart Island (performed by the extinct Stewart Is snipe C. aucklandica iredalei), there are few documented reports from other populations. We describe hakawai aerial displays heard on Adams I (Auckland Is snipe C. aucklandica aucklandica), Antipodes I (Antipodes Is snipe C. aucklandica meinertzhagenae), and Campbell I (Campbell Is snipe Coenocorypha undescribed sp.) between 2001 and 2006. These include the 1st records of hakawai on Adams I and Campbell I. Based on characteristic tail feather damage believed to be caused by the display, Campbell Is snipe of both sexes performed hakawai aerial displays more frequently than has been recorded for all other Coenocorypha snipe populations. Male snipe from all 6 populations assessed exhibited a higher frequency of tail feather wear than females, and for the 3 populations with adequate data, males also had lower wing-loadings, indicative of greater flying ability. However, there was no apparent correlation between the frequency of “hakawai” feather wear and wing-loadings when comparing between populations.
The kakapo (Strigops habroptilus) is a nocturnal, herbivorous parrot that shows lek behaviour and does not breed every year. When breeding does occur, egg-laying and incubation in mid-summer are followed by a prolonged period of chick-rearing, with all parental care provided by the female. Breeding years for kakapo are associated with mast seeding years for a range of forest trees and plants, and the periodicity of kakapo breeding is linked with the periodicity of years of large seed and fruit production by their major plant foods. Kakapo are likely to have an annual cycle of gonadal growth and regression driven by the annual cycle of day length, with breeding occurring in years when kakapo respond to cues from a range of plant species that undergo masting. Kakapo breeding is initiated in response to cues that appear in early summer, but in some years there is insufficient food for the rearing of young in the following autumn. Rimu (Dacrydium cupressinum) is an important food source for chick rearing and is likely to provide an important cue for kakapo in areas where rimu is present.
Between 1992 and 2002, the 4 main colonies of the king shag (Leucocarbo carunculatus) in the outer Marlborough Sounds, New Zealand were surveyed 10 times. Additional information was gathered at 2 smaller colonies off D’Urville Island. The average total population was estimated to be 645 birds, with 92% at Duffers Reef, Trio Islands, Sentinel Rock, and White Rocks, including 102-126 breeding pairs, with an annual recruitment of 40-68 birds. Surveys before 1992 may have included only c. 40% of the population, because most counts seem to have been done during the middle of the day when significant numbers of shags were absent feeding. If historic counts at colonies are adjusted for birds absent feeding, numbers appear to have been stable for at least the past 50 years — and possibly over 100 years — which would suggest a long-term balance between recruitment and mortality.
Vegetation in the Esperance Valley, Milford catchment, Fiordland, as it was in February and March 1974, is described using quantitative data for part of the valley that included home ranges of two male kakapo (Strigops habroptilus). One home range, of only 1.8 ha, was sited at 700 – 730 m altitude and extended over a gently-sloping river terrace covered in snow totara (Podocarpus nivalis) scrub with short silver beech (Nothofagus menziesii) forest at its margins. The other home range was 4 ha in area, sited on a very steep (42°) valley wall mantled with unconsolidated avalanche debris at 800-860 m altitude, faced NW and was covered by Blechnum capense fern – shrubland and short silver beech forest communities. At that time, this valley differed from most other parts of Fiordland: although possums (Trichosurus vulpecula), stoats (Mustela erminea) and rats (Rattus spp.) were present, ungulates were absent or very localised. Results gave no indication that food was limiting kakapo numbers in the Esperance Valley and we conclude that, because of the extreme vulnerability of females and their eggs, nestlings and fledglings to introduced mammalian predators, stoats were the most probable primary cause of kakapo decline in Fiordland.
The timing and breeding success of starlings (Sturnus vulgaris) in nest boxes was monitored simultaneously at 5 localities representing northern, central, and southern New Zealand. The northern locality, (Kaikohe, 35° 25’S) was monitored for 2 consecutive years; the others, of which Winton (46° 10’S) was the southernmost, for 4 consecutive years. The median date for the laying of Oct clutches was always earlier at Winton except in 1978 when it was 4 Oct at both Kaikohe and Winton. In any 1 year the size of Oct clutches (4.43 pooled over all years and localities) and the number of young in successful broods was always greater at Winton than elsewhere. In both 1977 and 1978 the difference in laying dates between Ohau and Waikanae (only 27 km apart) was greater than between Kaikohe and Winton at opposite ends of the country. The 5 localities showed no consistent trend, one with another, in their respective median laying dates from 1 year to another. The mortality of chicks was highest at Kaikohe, except for Belmont in 1978 when the 65% mortality was attributed to stoats (Mustela erminea). The laying of 2nd clutches has a very weak genetic basis and is probably a response to environmental factors.
The Campbell Is snipe (Coenocorypha undescribed sp.) was unknown to science until its discovery on 19 ha Jacquemart I in 1997. Following the successful eradication of Norway rats (Rattus norvegicus) from 11,268 ha Campbell I in 2001, there was increasing evidence that snipe had begun to recolonise the main island: footprints were found at Monument Harbour in 2003, and a fully-feathered dependent chick was captured nearby in Mar 2005. A survey of Campbell Is snipe recolonising Campbell I was undertaken by the authors and a trained bird-locater dog during 7-15 Jan 2006. We confirmed the presence of snipe and their successful breeding at 2 sites: the outlet to Six Foot Lake (head of Monument Harbour), and near the mouth of Kirk Stream at the head of Six Foot Lake. We estimated at least 22 adult snipe to be present. Twelve adult snipe were caught, along with 5 dependent chicks with estimated ages ranging from 8 to 37 d. One snipe nest was found. Subsequent sightings in Feb 2006 revealed at least 2 snipe to be present on the north-western shores of Perseverance Harbour, c. 3 km north of where we recorded them. We document the successful re-establishment of snipe on Campbell I within 5 years of rat eradication, and recommend that their natural recolonisation be left to continue unaided.
Seasonal changes in home range size and habitat selection of kakapo (Strigops habroptilus) were investigated on Maud Island. Kakapo were radio-tracked at night in each of the four seasons between December 2000 and October 2001. Home ranges were estimated for four adult males, three juvenile males and two juvenile females in each season and for nine females in summer, each based on 20 radio-fixes per season. Home range size varied from 1.8 to 145.0 ha using the minimum convex polygon method. Home ranges were smallest in winter. Habitat selection was determined by overlaying the kakapo locations and home ranges on a vegetation map of the island. For each season selection ratios were calculated for each vegetation community. Pine plantation (Pinus radiata) was selected for in summer, whereas the treeland community dominated by five-finger (Pseudopanax arboreus) was selected for in the autumn. Dense pole stands of manuka (Leptospemum scoparium) and pasture communities were avoided by kakapo.
We studied the New Zealand morepork (Ninox novaeseelandiae) over 2 breeding seasons on Mokoia I, Lake Rotorua, North Island, New Zealand. Ten pairs were monitored in the 1995/96 breeding season and 8 in the 1996/97 season. Nest sites included tree cavities, hollows amongst tree fern fronds, nest boxes provided for saddleback (Philesturnus carunculatus) and scrapes on the ground. Nest cavities were 0-5.2 m agl. Clutch size was 1-3 eggs; egg dimensions averaged 39.0 mm × 32.9 mm. The incubation period for 1 clutch was at least 24 days. Only females were observed to incubate eggs and brood nestlings; males roosted nearby. Two chicks were weighed and measured throughout their development and the nestling period was determined for 1 chick. Nestling development is described. Breeding success was lower in the year after a poisoning operation to eradicate mice from the island. Juvenile mortality was high after fledging. The dispersal of 3 juveniles was monitored, and females appeared to move earlier and disperse farther than males.
The context of modern conservation management of kakapo is introduced and a brief overview of the research presented in this special issue of Notornis is provided.
182 bird taxa have been recorded from the Chatham Is archipelago, including 32 reported here that are additional to the most recently published reviews in 1990 and 1994. Nine of these new records are from subfossil bone deposits; the remaining 23 are new records of vagrants or colonists, although 2 result from taxonomic revision of albatross species, where it is not clear how many terminal taxa had been recorded before 1994. Antipodean albatross (Diomedea antipodensis), Salvin’s mollymawk (Thalassarche salvini), and Indian yellow-nosed mollymawk (T. carteri) were recorded breeding on the Chatham Is for the 1st time since 1994, with the latter being the 1st breeding record for the New Zealand region. Notable among the list of over 100 vagrant species recorded from the Chatham Is are the only New Zealand records to date of Atlantic yellow-nosed mollymawk (T. chlororhynchos), and willie wagtail (Rhipidura leucophrys).